Mevalonic acid is a compound of the following formula: ##STR1## and is an intermediate in cholesterol biosynthesis. Mevalonic acid is biosynthesized from 3-hydroxy-3-methylglutaryl coenzyme A (abbreviated as HMG-CoA hereinafter) by the action of HMG-CoA reductase. Cholesterol in living body is not only biosynthesized according to the above route as well as being taken up from foods.
Until now, the determination of the quantity of biosynthesized cholesterol has been carried out by sterol-balance method. This method is complicated as it comprises subtracting the quantity of cholesterol in foods from the total cholesterol in feces, and therefore, in practice cannot be applied to clinical use.
In 1982, Parker et al. indicated that the quantity of biosynthesized cholesterol is extremely highly correlated to the concentration of mevalonic acid in plasma and revealed that the concentration of mevalonic acid in blood provides an indication of the quantity of biosynthesized cholesterol (J. Clin. Invest., 74, 795 (1984)).
Cholesterol in low density lipoprotein is said to be a contributory factor of arteriosclerosis. Arteriosclerosis can induce myocardial infarction, angina pectoris or cerebral infarction, and can ultimately lead to death.
In the treatment of hypercholesterolemia, it is necessary to judge whether hypercholesterolemia is caused by an excess of cholesterol biosynthesis or by an excessive intake of food high in cholesterol. Appropriate treatment can then be taken (for example, limitation of diet, or administration of HMG-CoA reductase inhibitor and monitoring the quantity of biosynthesized cholesterol after its administration).
Accordingly, it is very important clinically to know the quantity of biosynthesized mevalonic acid in order to assess disorders of lipid metabolism such as hypercholesterolemia.